Effects of Pore Morphology on the Fabrication and Mechanical Properties of Porous Si3N4 Ceramics
Porous Si3N4 ceramics with different pore morphology have been fabricated, utilizing either organic whiskers or starch as the fugitive agents, through slip-casting and die-pressing technique, respectively. The obtained porous ceramics have rod shaped or equiaxial pore morphology, originated from there two kinds of pore forming agents. The mechanical properties were investigated. The strength decreased considerably when small amount of whiskers were added, however, further increase in the whisker content only cause a moderate decrease of the strength. Gas permeability were measured for the samples with high whisker content of 60 vol% (corresponding to porosity of about 45% in the sintered bodies), and was compared with the counterpart contained the same porosity in which pores were equiaxial. The flexural strength of the samples with these two types of fugitive particles was almost the same, but the permeability of samples with rod-shaped pores were much higher than that with equiaxial pores, which can be understood in terms of a short pass model.
Wei Pan, Jianghong Gong, Chang-Chun Ge and Jing-Feng Li
J. F. Yang et al., "Effects of Pore Morphology on the Fabrication and Mechanical Properties of Porous Si3N4 Ceramics", Key Engineering Materials, Vols. 280-283, pp. 1231-1236, 2005